Max concurrent connections and TCP port limits

[Sad Clouds <cryintothebluesky%googlemail.com@localhost>]

Hi I was pondering about the absolute maximum number of concurrent TCP
connections a given machine can support. In the old days the limit was
dictated by the CPU speed and/or available memory.

Well, these days it seems the limit is TCP's 16-bit port numbers. If
you have a single NAT firewall, or a load balancer in front of many
machines, how can it support more than 65536 concurrent TCP connections?

One possible (the only?) way is to bind multiple IP addresses to the
same physical machine, then theoretically you can have a maximum of:

num_IP_addr * 2^16 concurrent TCP connections

Any idea if NetBSD TCP stack can handle such a case, i.e. can it reuse
the same ephemeral port number with different IP addresses?